Light-metal foams – some recent developments (original) (raw)

Process Parameters and Foaming Agents Used in Manufacturing of Aluminium metallic foams: A Review

Porous metals and metallic foams are composite materials in which one phase is gaseous and another phase is solid metal. The mechanical behavior of these materials depends mainly on the mechanical properties of the solid metallic phase, the structural configuration of the solid and the density of the composite ρc, relative to the density of the solid phase ρs. The primary distinction between a porous metal and metallic foam is the relative density, metal gas composites with a relative density (ρc/ρs) above 0.3 are generally considered porous materials, while those with a relative density below 0.3 are generally considered to be metallic foams or honey combs. Another distinction between the two is in the interaction between adjacent voids in the structure. Porous metals and metallic foams can have open cells, with completely interconnected voids, or closed cells, with each void being isolated by a solid film. This review outlines the process parameters and foaming agents used in manufacturing methods of Aluminium metallic foams and discusses benefits and concerns associated with their uses. Many research works have been done on this particular topic and various technologies have been proposed and applied at experimental and field levels.

Processing and Application of Aluminium Foams

2008

Foam is defined as a uniform dispersion of a gaseous phase in a liquid, separated by a thin film of liquid making a cell or pore. This morphology when preserved in solid state is known as solid foam or cellular solid. When we talk about metal foam, it is understood to have uniformly distributed gas pores in solid metal with volume fraction in the range of 40-98%. NEED OF METALLIC FOAMS The motivation behind the development of metal foams is due to their unique combination of physical and mechanical properties such as high stiffness, low specific weight, high gas permeability, low thermal conductivity, unusual acoustic properties, high impact absorption capacity and good electrical insulating properties. The potential applications of metal foams have been envisaged to be in the area of automotive industries, light weight construction materials, silencers, flame arrester, heaters, heat exchangers, catalysts, electrochemical applications, military armour vehicles and aircraft industries. D epending upon the requirements, several metals and alloy foams have been developed in the last three decades, e.

Review on Manufacturing of Metal Foams

ASM Science Journal, 2021

Metal foams possess excellent physical and mechanical properties. This paper reviews the common manufacturing process of metal foams. Various ways used to produce metal foams based on metal properties are described. The manufacturing process follows four primary routes: liquid state, solid state, ion or vapour processing. Liquid-state processing produces porosity to liquid or semi-liquid metals, and solid-state foaming produces metal foams with metal powder as starting material. For ion and vapour processing methods, metals are electro-deposited onto a polymer precursor. The polymer precursor is removed by chemical or heat treatment to produce metal foams. The advantages and limitations of each manufacturing process are also described.

An Overview of Aluminum Foam Production Methods

2021

Aluminium foams have become an attractive research field both from the scientif ic v iewpoint and the prospect of industrial applications. Various methods for making such foams are availab le. Some techniques start from specially prepared molten metals with ad justed viscosities. Such melts can be foamed by in jecting gases or by adding g as-releasing blowing agents which decompose in-situ, causing the formation of bubbles. A further way is to start from solid precursors containing a blowing agent. These can be prepared by mixing metal powders with a b lowing agent, compacting the mix and then foaming the compact by melting. A lternatively, casting routes can be used to make such precursors. Aluminium foam is a type of cellular solid having a combination of properties such as high stiffness with very low density and a capability to absorb impact energy. These unique combinations of properties indicate various potential applications such as machinery enclosures, automobile sector, av...

DEVELOPMENT AND EVALUATION OF DENSITY AND PORSITY OF ALUMINIUM FOAMS

The characteristic of metal foams is a very high porosity typically 75–95% of the volume consists of void spaces making these ultra light materials. The strength of foamed metal possesses a power law relationship to its density; i.e., a 20% dense material is more than twice as strong as a 10% dense material. Methods for producing metal foams are many, but obtaining repeatability in the properties is very difficult. The main challenge posed by the metal foam is that obtaining homogeneous porosity. Metal foams are a new kind of materials with low densities and novel physical, mechanical, thermal, and electrical properties. They can be divided into closed cell and open cell structures Although lot of problems involved in the development of metal foams, research people are attracted to the metal foams because of its attractive properties like acoustic damping, bomb mitigation, light weight etc. By considering the development of Aluminium foams as important aspect, some methods have been adopted and attempts have been made to produce metal foams at lower cost using a different foaming agent which are cheaper than the conventional foaming agent. The methods developed for the Aluminium foams were Aluminium foam production using NaCl crystal as a place holder in the Al melt, Aluminium foam production using NaCl crystal as a place holder in sand salt mould, Aluminium foam production using NaCl crystal as a place holder by simultaneous pouring i.e., fusion including both foaming agent and salt concept. The problems associated in each process and its effect on the density and porosity of the foam are discussed.

Metal foams for structural applications: design and manufacturing

International Journal of Computer Integrated Manufacturing, 2007

In this paper, the design and manufacture of metal foams, using the powders compact melting method (PCMM), is investigated. Experimental tests were performed to study the influence of several process parameters, that is, compaction pressure, foaming time, temperature and amount of foamable precursor material, on the kinetics of foaming process. As the large number of experimental factors involved in metal foams manufacturing, an experimental approach based upon DOE techniques was employed to reduce the trials need for individuating the best process windows. Hence, in such operative ranges, further experimental tests were carried out to trace the full trends of foaming efficiency according to leading parameters, thereby laying the basis to support manufacturers on how to deal with the operative troubles and process settings.

Characteristics, applications and processing of aluminium foams -A Review

Elsevier, 2021

Metal foams well-known for there lightweight and wide applications especially the energy absorbing property. These foams consist of 5 to 25% metal and 75 to 95% of gas. Among metallic foams, aluminium foams find their application in many domains like architectural design, light weight construction, orthopaedic, automotive industries, energy absorption, acoustics and thermal applications. The mechanical behaviour of the aluminium foams and the thermal effects on them were studied. Different processing methods to improve the foamability and strengths are also discussed. This paper overviews the physical, mechanical and thermal behaviour of the aluminium foams, their processing methods, their applications, testing and validation of properties for specific requirements.

Metal foams manufacture and physics of foaming

The various ways to produce metal foams are reviewed. An analogy to aqueous foams is drawn and exploited to discuss the principle mechanisms responsible for foam stability. Experimental work based on ex situ metallography and in situ radioscopy of metal foam formation is used to answer some questions associated with the physics of foaming and to define areas where further research is still needed